In recent studies the applicant has demonstrated that cholecystokinin (CCK) antagonizes opiate-specific analgesia. Several lines of evidence suggest that CCK has effects opposite from those of opiates on other functions such as food intake. In this application for a level I RSDA, I propose to study the neuroanatomical organization of CCK and opiate systems in specific brain regions concerned with nociception and food intake and will seek evidence for neuroanatomical contacts between CCK and opiate systems through which modulatory effects of one system upon the other might occur. In addition, by biochemical, pharmacological and behavioral approaches I will seek further evidence for an interactive relationship between CCK and opiate systems in the regulation of nociception and food intake. My prior training has been primarily in behavioral and pharmacological methods. The research proposed herein will provide supervised training in a wide range of additional techniques (light and electron microscopic immunohistochemistry, receptor ligand autoradiography, retrograde and anterograde transmitter pathway tracing, selective neurochemical lesioning, radioimmunoassay, high performance liquid chromatography and receptor binding assays).